Backstand idler



Sept. 3, 1957 Filed Aug. 17, 1955 G. w. JOHNSON BACKSTAND IDLER 2Sheeis-Sheet l George Johnson Sept. 3, 1957 e. w. JOHNSON BACKSTANDIDLER 2 Sheets-Sheet 2 Filed Aug. 17, 1955 BACKSTAND IDLER George W.Johnson, Rockford, 11]., assignor to Fenlind Engineering Co., LovesPark, 11]., a corporation of Illinois Application August 17, 1955,Serial No. 528,934

12 Claims. (Cl. 51-148) This invention relates to a new and improvedbackstand idler for use with the endless belt used on grinding andpolishing machines to keep the belt properly tensioned and running trueat all times with minimum need of attention on the part of the operatoronce the necessary adjustments have been made.

The principal object of my invention is to provide a backstand idler ofsimpler and more economical construction providing improved belttensioning and tracking adjustments for the idler pulley so that it isnot necessary to have absolute center alignment between the idler pulleyand the contact wheel and yet the abrasive belt can be kept running truewith minimum need for attention on the part of the operator, and as aresult better grinding can be done and greatly increased production isobtainable.

The invention is illustrated in the accompanying drawings, in which Fig.1 is a perspective view of a grinder showing a backstand idler made inaccordance with my invention, mounted on the floor behind it, althoughit will be understood that bench or wall mountings may also be used;

Fig. 2 is a plan view of the backstand idler With the abrasive beltremoved, this device having a left-hand tilting adjustment, asdistinguished from the right-hand tilting adjustment shown in Fig. 1;

Fig. 3 is a side view of Fig. 2;

Fig. 4 is a front end view on line 4--4 of Fig. 3, and

Fig. 5 is an enlarged detail of a portion of Fig. 4.

The same reference numerals are applied to corresponding partsthroughout the views.

Referring to the drawings, the reference numeral 5 designates a grinderor front stand having the contact wheel 6 detachably secured to thedrive shaft 7 thereof to permit appli ation of contact wheels ofdifferent diameters and widths, depending upon the grinding job to beperformed with the endless abrasive belt. These belts also come invarious widths, one of these coated abrasive belts being indicated at 8running on wheel 6 and over an idler pulley 9 on the backstand idler,indicated generally by the reference numeral 10. An elongated crank 11extends forwardly from the backstand idler to the operators station atthe grinder 5, and by manipulation of the handle 12 the tension in belt8 may be increased or decreased as necessary. Another elongated crank 13having an operating handle 14 on its front end is operable in similarmanner from the operators station at the front of the grinder to makethe belt 8 run true by tilting adjustment of the pulley 9, and aspreviously indicated, the present invention is particularly concernedwith improve ments in the backstand idler concerned with the tension andtilting adjustments with a view to greater simplicity and economy ofconstruction and avoiding one-side stretch of the abrasive belt andobtaining more even grinding under all conditions.

The backstand idler comprises a supporting base consisting of front andrear brackets 15 and 16 in which parallel guide rods 17 are suitablyfixedly mounted for slidable support of the idler pulley carriage 18. Acoiled ate i 2,804,726 Patented Sept. 3, 1957 ice compression spring 19surrounds a shaft 20 mounted between the guide rods 17 for rotation inbearings 21 in frames 15 and 16 and held against endwise displacement bya collar 22 that is pinned to the forward end of the shaft, as indicatedat 23. The shaft is threaded, as indicated at 24, and threads in a nut25 that is held against rotation by slidable engagement with the bottomof a housing 26 in which the spring 19 is held caged between the nut 25and the rear end wall of the housing, whereby normally to urge thehousing 26 rearwardly and thereby, through the link connection indicatedat 27 with the carriage 18, apply tension resiliently to the abrasivebelt 3 running on idler pulley 9. A bell-crank lever 28 that ispivotally mounted, as at 29, on the carriage 18 and has pivotalconnection, as indicated at 30, with the front end of the link 27provides a means of quickly releasing the belt tension by moving thelever 28 in a clockwise direction about the pivot 29 so as to move thepivot 34) past deadcenter with respect to the pivot 29 and pivotalconnection 31 of link 27 with the housing 26 and accordingly release thepressure of spring 19 on housing 26 and carriage 18 connected with itthrough link 27. The protruding front end portion of shaft 20 has oneyoke of a universal joint 32 (Fig. l) suitably secured thereto forrotary adjustment of the shaft 20 by means of crank 11 and handle 12 sothat the tension on the belt 8 may be increased or decreased from theoperators position to a fine degree.

Tilting adjustment of the idler pulley 9 to obtain proper tracking ofbelt 8 is obtained by infinite adjustment of the length of the linkconnection 33 provided between the base plate 34, that is bolted to thecarriage 18, as indicated at 35, and an arm 36 that extends forwardlyfrom the vertical arm 37 of a bell-crank bracket 38, 011 which the arbor39 for support of the idler pulley 9 is carried. The bracket 38 isadapted to be adjusted by this link connection to whatever minuteangular degree may be necessary about its pivotal connection 46 with thebase plate 34. The horizontally extending arm 41 of the bell-crankbracket 38 extends under the pulley 9 and slidably engages the back ofthe base plate 34 as an abutment, as clearly appears in Fig. 4, thepivot 40 being disposed in avertical plane passing through the middle ofthe pulley 9. The link connection 33 comprises upper and lower sets oftoggle links 42 and 43, respectively, the upper links 42 having apivotal connection with the ends of a cross-bar 44, the enlarged middleportion 45 of which is received in an opening 46 in the outer end of thearm 36, while the lower links 43 are pivotally connected to the ends ofanother cross-bar 47, the enlarged middle portion 48 of which isreceived in a hole 49 provided in one end portion of the base plate 34,the left-hand end of this generally U-shaped base plate being used for aleft-hand unit, like that shown in Figs. 2 to 4, whereas the right-handend is used in the case of a right-hand unit like that shown in Fig. l.The enlarged middle portions 45 and 48 of cross-bars 44 and 47,respectively, are spheroidal-shaped to provide the universal jointaction required with the tilting adjustment of the bracket 38 withrespect to the base plate 34. For the same reason, the washers providedat 50 and 51 between the links 42 and bearing 46 on the one hand, andbetween the links 43 and the bearing 49 on the other hand, are rubberwashers for compressibility thereof to whatever degree may be necessarywith different adjustments of the bracket 33, so that there need be nolooseness in the pivotal connections, which might otherwise give rise tovibration and noise in the operation of the backstand idler.

These rubber washers also serve to seal the bearings 46 and 49 againstentry of grit and dirt, so that easier operation and longer wear areassured. A collar 52 has a shaft 53 rotatable therein and this shaft isheld against end wise movement by an annular shoulder 54 provided on theshaft and abutting one side of the collar, and a ring 55 that is pinnedto the shaft and has abutment on the other sideof the collar; The shaft'53 is threaded, as in-- dicated at 56, and has a nut 57 threadingthereon. 'lirunnions. 58 on oppositesidesof the collar 52 and trunnions59 on opposite sides of the nut 57 provide pivotal connections for theinner ends: of the links. 42 and 43 with the collar 52 and nut 57. Theoppositeends 60 and 61 of the shaft 53 are squared, the. front end 60:having one yoke 62 of auniversal joint attached thereto to provideconnection with the crank 13, as shown in Fig. 1. When the shaft 53 isturned clockwise, nut 57 moves toward collar 52 to elongate theparallelogram defined by the toggle links 42-43 in a vertical direction,and the link connection 33 isaccordingly increased inlength, and viceversa when the parallelogram 42-43 is elongated in a horizontaldirection; The adjustment in one: direction (for lengthening linkconnection 33) is limited by engagement of nut 57 withcollar 52, and inthe other direction (for i shorteninglink connection 33) by engagementof nut 57 withthe front of the bracket 38. The shaft 53 extends througha slot 63 provided in the vertical arm 37 of the bracket 38 to provideoperating clearance in a vertical direction for the shaft in theshortening and lengthening of the link connection 33.

It is believed the foregoing description conveys a good understanding ofthe objects and advantages of my invention. The appended claims havebeen drawn to cover all legitimate modifications and adaptations.

I claim:

in agrinding and polishing machine including a front stand having amotor driven contact wheel and acoated abrasive belt trained thereon, abackstand comprising a base, an idler pulley having said belt alsotrained thereon, an- L-shaped bracket carrying a horizontal arbor on itsvertical leg supporting said pulley, said bracket being pivotallymounted by its horizontal arm on said base on a substantially horizontalaxis spaced laterally from saidvertical leg and in a vertical planepassing through the middle of said pulley, and an adjustable lengthsupport for the bracket rigidly connecting the base and bracketinradially spaced relation to said pivotal axis to tilt the pulleyrelative to the vertical plane and hold it in tilted position.

2. In a grinding and polishing machine including a front stand having amotor driven contact wheel and a coated abrasive belt trained thereon, abackstand comprising a base, a carriage slidable back and forth on saidbase toward and away from the front stand, means for adjusting it awayfrom the front stand for belt tensioning, an idler pulley mounted onsaid carriage and having said belt trained thereon, means defining anabutment transversely of said' carriage, an L-shaped bracket carrying onits vertical leg a substantially horizontal arbor supporting saidpulley, said bracket having its horizontal leg'slidably engaging saidabutment and pivoted relative thereto on a substantially horizontal axisspaced laterally from said vertical leg and in a vertical plane passingthrough the middle of said pulley, and a manually adjustable connectionbetween said carriage and said bracket in radially spaced relation tosaid axis whereby said pulley is tiltable relative to the vertical planeand held in tilted position.

3. in a grinding and polishing machine including a front stand having amotor driven contact wheel and a coated abrasive belt trained thereon, abackstand comprising a base, an idler pulley having said belt alsotrained thereon, a bracket carrying an arbor supporting said pulley,said bracket being pivotally mounted on said base on a substantiallyhorizontal axis in a vertical plane passing through the middle of saidpulley, and an adjustable length support for said bracket rigidlyconnecting the base and bracket in radially spaced relation to saidpivotal axis to tilt the pulley relative to the vertical plane and holdit in tilted position.

4. In a grinding and polishing machine including a front stand having amotor driven contact wheel and a coated abrasive belt trained thereon, abackstand comprising a base, an idler pulley having said belt alsotrained thereon, a bracket carrying an arbor supporting said pulley,said bracket being pivotally mounted on said base on a substantiallyhorizontal axis in a vertical plane passing through the middle of saidpulley, and an adjustable length support for said bracket rigidlyconnecting the base and bracket in radially spaced relation to saidpivotal axis to tilt the pulley relative to the vertical plane, saidadjustable length support comprising a toggle linkage defining aparallelogram structure extensible in a vertical direction forelongation of the support and extensible in a horizontal direction forshortening the support, two opposed corners of the structure beingconnected to the base and bracket, and manually adjustable meansadjustably connecting the other two opposed corners of the structure.

5. In a grinding and polishing machine including a front stand having amotor driven contact wheel and a coated abrasive belt trained thereon, abackstand comprising a base, a carriage slidable back and forth onsaidbase toward and away from the front stand, means for adjusting it awayfrom the front stand for belt tensioning, an idler pulley mounted onsaid carriage and having said belt trained thereon, means defining anabutment transversely of said carriage, a bracket carrying an arborsupporting said pulley, said bracket slidably engaging said abutment andpivoted relative thereto on a substantially horizontal axisina verticalplane passing through the middle of said pulley, and a manuallyadjustable connection between said carriage and said bracket in radiallyspaced relation to said axis whereby said pulley is tiltable relative tothe vertical plane and held in tilted position.

6. In a grinding and polishing machine including a front stand having amotor driven contact wheel and a coated abrasive belt trained thereon, abackstand comprising a base", a carriage slidable' back and forth onsaid base toward and away from the front stand, means for adjusting itaway from the front stand for belt tensioning, an idler pulley mountedon said carriage and having said belt trained thereon, means defining anabutment transversely of said carriage, a bracket carrying an arborsupporting said pulley, said bracket slidably engaging said abutment andpivoted relative thereto on a substantially horizontal axis in avertical plane passing through the middle of said pulley, and a manuallyadjustable connection betweensaid carriage and said bracket in radiallyspaced relation to said axis whereby said pulley is tiltable relative tothe vertical plane, said manually adjustable connection comprising atoggle linkage defining a parallelogram structure extensible in avertical direction for elongation of the connection and extensible in ahorizontal direction for shortening the connection, two opposed cornersof the structure being connected to the carriage and bracket, andmanually adjustable means adjustably connecting the other two opposedcorners of the structure.

. in a grinding and polishing machine including a front stand having amotor driven contact wheel and a coated abrasive belt trained thereon, abackstand comprising a base, an idler pulley having said belt alsotrained thereon. a carriage for said idler slidable back and forth onsaid base toward and away from the front stand, a rotatabl'y adjustablescrew carried on said base longitudinally thereof under said carriagehaving a nut threaded thereon and abutting one end of a compressionspring that surrounds the screw, a housing through which the screwextends for rotation with respect thereto and in which the nut hasslidable engagement with one wall thereof to prevent turning of the nutwhile the spring has abutment with another Wall thereof to transmit the.ad-

justable spring pressure to said housing,rmeans at one end nected at oneend to said housing, and a manually operable bell-crank lever pivotallymounted at one point on said carriage and pivotally connected at anotherpoint to the other end of said link, so as to permit moving the latterpivot from one side to the other of a dead-center with respect to thelevers pivot on the carriage and the links pivot on the housing, wherebyto apply tension to the belt or relieve the same of tension.

8. In a grinding and polishing machine including a front stand having amotor driven contact wheel and a coated abrasive belt trained thereon, abackstand comprising a base, an idler pulley having said belt alsotrained thereon, an L-shaped bracket carrying a horizontal arbor on itsvertical leg supporting said pulley, said bracket being pivotallymounted by its horizontal arm on said base on a substantially horizontalaxis spaced laterally from said vertical leg and in a vertical planepassing through the middle of said pulley, and an adjustable lengthsupport for the bracket rigidly connecting the base and bracket inradially spaced relation to said pivotal axis to tilt the pulleyrelative to the vertical plane and hold it in tilted position, saidadjustable length support comprising a toggle linkage defining aparallelogram structure extensible in a vertical direction forelongation of the support and extensible in a horizontal direction forshortening the support, two opposed corners of the structure beingconnected to the base and bracket, and manually adjustable meansadjustably connecting the other two opposed corners of the structure.

9. In a grinding and polishing machine including a front stand having amotor driven contact wheel and a coated abrasive belt trained thereon, abackstand comprising a base, a carriage slidable back and forth on saidbase toward and away from the front stand, means for adjusting it awayfrom the front stand for belt tensioning, an idler pulley mounted onsaid carriage and having said belt trained thereon, means defining anabutment transversely of said carriage, an L-shaped bracket carrying onits vertical leg a substantially horizontal arbor supporting saidpulley, said bracket having its horizontal leg slidably engaging saidabutment and pivoted relative thereto on a substantially horizontal axisspaced laterally from said vertical leg and in a vertical plane passingthrough the middle of said pulley, and a manually adjustable connectionbetween said carriage and said bracket in radially spaced relation tosaid axis whereby said pulley is tiltable relative to the vertical planeand held in tilted position, said manually adjustable connectioncomprising a toggle linkage defining a parallelogram structureextensible in a vertical direction for elongation of the connection andextensible in a horizontal direction for shortening the connection, twoopposed corners of the structure being connected to the carriage andbracket, and manually adjustable means adjustably connecting the othertwo opposed corners of the structure.

10. In combination, a base, a pulley adapted to have a belt trainedthereon, a bracket carrying an arbor supporting said pulley, saidbracket being pivotally mounted 6 on said base on an axis in a planepassing through the middle of said pulley, and an adjustable lengthsupport for said bracket rigidly connecting the base and bracket inradially spaced relation to said pivotal axis to tilt the pulleyrelative to the aforesaid plane and hold it in tilted position, saidadjustable length support comprising a toggle linkage defining aparallelogram structure extensible in one direction for elongation ofthe support and extensible in a direction at right angles to the firstmentioned direction for shortening the support, two opposed corners ofthe structure being connected to the base and bracket, and manuallyadjustable means adjustably connecting the other two opposed corners ofthe structure.

11. In combination, a base, a carriage slidable back and forth on saidbase, a pulley mounted on said carriage and adapted to have a belttrained thereon, means defining an abutment transversely of saidcarriage, a bracket carrying an arbor supporting said pulley, saidbracket slidably engaging said abutment and pivoted relative thereto onan axis in a plane passing through the middle of said pulley, and amanually adjustable connection between said carriage and said bracket inradially spaced relation to said axis whereby said pulley is tiltablerelative to the aforesaid plane and held in tilted position, saidmanually adjustable connection comprising a toggle linkage defining aparallelogram structure extensible in one direction for elongation ofthe connection and extensible in a direction at right angles to thefirst mentioned direc tion for shortening the connection, two opposedcorners of the structure being connected to the carriage and bracket,and manually adjustable means adjustably connecting the other twoopposed corners of the structure.

12. In combination, a base, an L-shaped bracket having one leg of the Ldisposed substantially parallel to said base and pivotally connectedthereto at its outer end, the other leg of the L being disposedsubstantially at right angles to said base, and a tilting adjustment forsaid bracket comprising an adjustable length support connecting the lastmentioned leg of said L with said base in spaced relation to theaforesaid pivot, said adjustable length support comprising a togglelinkage defining a parallelogram structure extensible in one directionfor elongation of the support and extensible in a direction at rightangles to the first mentioned direction for shortening the support, twoopposed corners of the structure being connected to the base andbracket, and manually adjustable means adjustably connecting the othertwo opposed corners of the structure.

References Cited in the file of this patent UNITED STATES PATENTS1,108,176 Hormel Aug. 25, 1914 1,939,674 Elskamp Dec. 19, 1933 2,507,372Emmons May 9, 1950 2,578,662 Bader Dec. 18, 1951 2,624,158 HendricksonJan. 6, 1953 2,721,423 Haussler Oct. 25, 1955 g

